DE329542C - - Google Patents

Description

Process for the decomposition of air into oxygen and nitrogen under simultaneous extraction of high percentage argon. In the known apparatus for Separation of the air components by liquefaction becomes the liquid oxygen, the lower part of the rectification column named "evaporator" arrives, evaporates in this part itself at the expense of the compressed air to be treated. About 4 / "of the oxygen vaporized in this way rises in the rectification column upwards, in order to gradually transform the introduced fluids into fluids To convert oxygen, replacing the previous one. The last '/ "which is the oxygen corresponds to the treated air, emerges directly from the apparatus and forms one of the manufactured products. The ascending case, which during their Ascent is progressively converted when the fluids are touched, kick on the other hand as nitrogen. Due to the presence of argon in particular, In practice, however, the gates are by no means that easy. The argon, the boiling point of which is very close to that of oxygen, separates with great difficulty from this, and for the production of very pure oxygen, which is always used in industry is more popular, must be a considerable together with the argon on the nitrogen side Some of the oxygen in the treated air will be pushed back, which will reduce the yield decreased in oxygen and the value of nitrogen depleted.

In the French patent 437013 of February 6, 191z, the FIGS. 1 and 2 of which are reproduced in the accompanying drawing, a means for eliminating the last-mentioned deficiency and for obtaining very pure oxygen without harming the purity of the nitrogen is given. This means consists in letting the liquid oxygen corresponding to the above-mentioned flow into a special space (Fig. 1), where it is separated by rectification and evaporation: partly into a small amount, almost the total amount of nitrogen and the argon-entraining part, the other part in a main mass formed from almost pure oxygen. The first word ion, which is removed separately through the connection piece W, therefore does not contaminate the nitrogen supplied by the main rectification column in any way with its oxygen and argon. According to the aims pursued by the patent, the system for liquefying the compressed air by means of the oxygen to be evaporated can be any, e.g. B. a coil S (Fig. 2).

However, this procedure does not eliminate Away the Above mentioned disadvantage of an insufficient yield of pure oxygen, as a considerable part of this gas at the point W mixed with nitrogen and Argon leaks.

The present invention relates to an improvement according to which . The mixture of nitrogen, argon and Oxygen is treated in such a way that the oxygen which strives with the nitrogen and argon to escape through W is retained.

According to the new process, this becomes very oxygen-rich, but still Mixture containing nitrogen and argon, which the lower parts of and taken for-itself known apparatus for breaking down the air into its components is converted into three factions, namely: into a faction that, practically taken, all of the nitrogen it contains, in a second fraction, which is made up almost pure oxygen, and in a third, so to speak nitrogen-free fraction that consists of Argon is mixed with a certain amount of oxygen by weight.

For this purpose, the one produced in the usual rectification column is used liquid oxygen, which is almost the total amount of argon in the air and treated contains some nitrogen, in a liquefaction and rectification auxiliary circuit introduced, in which a mixture of these three gases, but very rich in argon, in certain Crowd circles. This gas is compressed, then liquefied and in a liquid state for the rectification of the impure liquid oxygen evolving from the aforementioned Used fumes. This last liquid produced flows downwards with the through the auxiliary rectification obtained via rectification trays, as shown in Fig. z and 2 illustrate. This increases the degree of purity in terms of oxygen of the liquid, while argon, which is the main impurity of the liquid oxygen formed, at the top of the auxiliary rectification serving part the column, with the entrainment of very little oxygen, escapes, namely in gaseous state together with the argon of the auxiliary circuit. What the in the initial When nitrogen containing impure liquid oxygen arrives, it escapes also with the argon of the two previous origins. But you can do that closed Take the circulating argon-rich volume so large that the small amount of nitrogen which was contained in the impure liquid oxygen being treated and in the exiting Argon finds itself for the most part, forming a weak fraction that is practically negligible. This very little nitrogen-rich argon The amount of argon to be discharged to the outside is withdrawn from the mixture corresponds to those who are unclean; liquid oxygen of the main column was introduced.

The one that is not discharged to the outside, i.e. that remains behind and closed The circulating part of the argon mixture is compressed again and flowing back the liquefied parts liquefied to one hand 'strongly argon-containing liquid to deliver, which, as shown above, serves again as rectification liquid, and on the other hand to leave a nitrogen-rich residue which is practical contains all the nitrogen that is discharged to the outside, which prevents that this gas accumulates in the circuit:.

In order to provide the auxiliary circuit with the gas it needs to develop, one simply makes use of the gases that are released from the develop impure liquid oxygen leaving the main column. These gases are compressed and liquefied and have in the auxiliary circuit described above the endeavor to develop into the aforementioned argon-rich mixture, what occurs according to the well-known process of self-purification, according to which each Gas mixture strives to enrich itself with the most volatile of its constituents, what enrichment by scrubbing the gases by means of their reliquefaction originating fluids is effected. It goes without saying that during this operation no gas removed to the outside, since the argon is only removed when its content is high enough.

Fig. 3 shows one for practicing the new. Procedure suitable Apparatus, in its upper part, consists of an evaporator K and a rectification column I_ existing part the air is broken down in a known manner. In these well-known Part of the apparatus is the air to be treated on the one hand through the connection A below Pressed and cooled, otherwise introduced at the point T "in the liquid state. The liquefaction itself takes place in the serpentine pipe S, which is discussed further on is detailed. This in this way in the known part of the apparatus introduced air will. in nitrogen and in a liquid, very oxygen-rich; but still argon and nitrogen containing mixture decomposed, which in the evaporator K accumulates, whereas the nitrogen mentioned in the first place ari through the upper one Port B of the rectification column escapes.

The lower part of the apparatus forming the subject of the invention comprises the secondary rectification column R ', the evaporator G, the tube bundle F intended for partial liquefaction, the liquefaction coil tube S, the heat exchanger E and the compressor C. In these individual organs takes place the above-mentioned decomposition of the oxygen-rich, but still argon and nitrogen containing, in the evaporator K accumulating mixture.

For the purpose of treatment, the very rich in oxygen, an-argon and nitrogen less rich mixture through tube T from the main rectification column transferred to the lower plate of the secondary column R ', where it is in countercurrent wandering down from plate to plate to the rising gases and thereby becoming part of it Oxygen enriches. -The exit of the mixture entering the evaporator G. becomes an equivalent due to the total liquefaction taking place in the coiled pipe S. Balanced amount of compressed air that is in liquid form at point T "in the main column enters.

Those escaping through the nozzle W at the top of the secondary column Gases first flow through a heat exchanger E and arrive; then into the compressor G where they are condensed. Then they flow anew in the opposite sense through exchanger E and return to that which is immersed in evaporator G. Tube bundle F, where they partially liquefy again. The one from this liquefaction resulting weak gas residue is removed at point H and consists of The main thing is from all the nitrogen that is in the W from the secondary column escaping gases was contained, whereas the liquid produced was therefore only still contains oxygen and argon.

This liquid is now at the point T 'in the upper part of the Secondary column introduced, and there, apart from small losses, which in the Bundle F the amount of liquid produced on the outside of this bundle Evaporation is equivalent to the amount of gas rising in the column, so the amount of liquid which can be supplied to the point T 'is not subject to any restrictions. Rather, we are dealing with a closed auxiliary circuit in which there is endless moves an equal amount of gas, which is usually larger in: incomparable measure is than the amount of liquid flowing in through tube T, so that that in the secondary column rectification processes taking place primarily through the liquid content this auxiliary circuit, but very little through the quantum flowing out of the pipe T. be mastered. The liquid generated in the tube bundle F consists of a nitrogen-free mixture of argon and oxygen. From this and under the influence that by washing the gases by means of reliquefaction of these gases resulting liquid, on the well-known processes of self-cleaning traceable phenomena, the result is that the gases withdrawn at .W are at Starting the apparatus increasingly with the most volatile element of the mixture, namely the argon.

_ What the nitrogen contained in the mixture flowing out of the pipe T is reached, cr, due to its greater volatility, reaches the point in toto W in the upper part of the Se?: Undärl: olonne, but occurs there only in very small quantities because the argon and oxygen mixture flowing in the auxiliary circuit is relative is enormous and is withdrawn from the tube bundle F. The flowing off at the point W. Gases therefore always contain only an extremely small part by weight of nitrogen, which, if necessary, can still be reduced to less than one percent. These Gases therefore represent a mixture that is very rich in argon and practically nitrogen-free is. As soon as the normal work process has set in, you can go there h a portion of this approximately equal to the total argon supplied through tube T. Draw off argon and oxygen mixtures as a manufactured product.

From what has been said it can be seen that this is too. The treatment mixture consisting of oxygen, argon and nitrogen is broken down by the new process: into a fraction that contains all of the nitrogen and is removed at 1-I, into another fraction consisting of practically pure oxygen, which can be removed at point U, and in a third fraction that can be drawn off at Y, which consists of a practically nitrogen-free mixture of argon and oxygen. The present process therefore avoids the considerable loss of oxygen which results from the use of the process according to French patent .f37013 . If the evaporation of the gases circulating in the rectification column is quantitatively ensured by -the liquefaction of the compressed gas in the liquid oxygen (apart from the quantities of nitrogen and argon withdrawn), then it goes without saying that the evaporation of the oxygen, which is one of the manufactured products forms and withdraws through the nozzle U, is achieved in the pipe system S at the expense of part of the treated air. About 4; 5 of this air must be liquefied in the pipe system K, K 'of the main apparatus and about x /, in the pipe system S of the chamber G, from which the generated liquid is passed up through pipe T ″ to the main column, around the outlet of the liquid Balance oxygen through tube T.

Claims (3)

PATE I \ TT CLAIMS: i. Process for the decomposition of air into oxygen and nitrogen with simultaneous recovery of high-proof argon, by which Liquefaction and rectification of the air on the one hand pure oxygen and on the other hand Argon-rich vapors are obtained, characterized in that the argon-containing Vapors through an argon-rich, oxygen-containing, practically nitrogen-free liquid rectified, compressed and then with backflow of the liquefied parts are liquefied so as to practically remove all the nitrogen they use contain, to enable and the rectification liquid required again and again to deliver, the argon-rich gases circulating in such a way in such quantities be used that the nitrogen contained in the oxygen-rich liquid found in them only in very small proportions. 2. Procedure according to Claim i, characterized in that the nitrogen-free mixture is in gaseous form State in which the liquefied parts were liquefied with backflow, very rich in argon Mixture is withdrawn and the liquid generated at the same time in the -I-auxiliary rectification column is introduced where the very argon-rich gas mixture escapes. 3. Procedure according to claim i, characterized in that the very oxygen-rich Liquid at the same time to liquefy part of the treated compressed Air is used, the liquid of which is then used in the main rectification, and at the same time to liquefy the very argon-rich mixture "of it with backflow The liquid generated from the liquefied parts is then used for auxiliary rectification finds. q .. Device according to claim i, 2 and 3, characterized in that the Auxiliary rectification column has two evaporators (S and F) at its lower part, one of which (F) is set up for the return flow of the liquefied parts is, -wherein the liquid generated in (F) into the upper end of the auxiliary rectification column is introduced through a valve fitted with a pipe (T '), while the out the upper part of the column at the point (W) escaping gases over an exchanger (E) and a tap (Y) serving to remove the very argon-rich gas: into one Compressor (c) is introduced, which sends the compressed gases to the exchanger (E) and then to the evaporator (F) again, whereby the in the evaporator (S) liquid formed through a pipe (T ") fitted with a tap, up to a suitable point in the main rectification column will.